The overall objective of this collaborative project is to characterize small nucleic acids (SNAs) that were concurrently discovered by two laboratories in Leishmania and Endotrypanum. The small size, multicopy nature, restriction to a few stocks, and change in copy number upon culture stress indicates that these SNAs are viral, extrachromosomal, or amplified chromosomal sequences. Experiments are proposed to 1.) Characterize the physiochemical properties of SNAs including determining their size, if they are DNA or RNA, linear or circular, and single or double stranded. THe SNAs will be mapped, their sequence similarity will be assessed by cross hybridization, and they will be cloned to provide material for more detailed analyses. 2.) Establish the general biological properties of SNAs. Their subcellular and possible chromosomal location will be examined. Their possible release from cells and their potential transmissibility by infection and DNA transformation will be tested to explore their potential viral nature and their potential as cloning vectors. 3.) Examine the general genetic organization of SNAs. The physical and transcriptional organization of one or two selected SNAs will be examined in greater detail to identify genetically active and regions essential and non-essential to the transmission and intracellular maintenance of the SNA. A multipronged collaborative effort is proposed to generate sufficient comparative information to determine the relationship, if any, among these SNAs, to select the appropriate SNAs for intensive analysis, and to provide for an exchange of materials and ideas. These naturally occurring SNAs have immense potential as molecular cloning vectors that will be valuable for the study of critical parasite processes. In addition, they may normally perform functions of vital importance to the parasites and of importance to understanding host parasite interactions, disease characteristics and pathology. The SNAs present a novel opportunity to use modern biotechnological approaches to understand important parasite processes and to develop creative strategies for disease control.